2-Ethylhexanoic acid: subchronic oral toxicity studies in the rat and mouse.

Groups of 10 male and 10 female Fischer 344 rats and B6C3F1 mice were fed diets containing either 0.0, 0.1, 0.5 or 1.5% 2-ethylhexanoic acid (EHA) for 13 wk. Additional groups of 10 male and 10 female rats or mice. were fed either 0.0 or 1.5% EHA for 13 wk followed by a 4-wk recovery (non-treatment) period. Based on food consumption and body weight, the EHA diets provided doses of 61, 303 or 917 mg/kg/day for male rats and 71, 360 or 1068 mg/kg/day for female rats. The EHA diets provided doses of 180, 885 or 2728 mg/kg/day for male mice and 205, 1038 or 3139 mg/kg/day for female mice. No mortality or significant clinical signs of toxicity were observed during the study. Body weights and food consumption of both rats and mice fed 1.5% EHA were lower beginning after the first week of treatment, consistent with a reduction in food consumption. Other groups were unaffected by treatment. After 13 wk, lower triglyceride levels occurred in male mice fed 1.5% EHA and female mice fed 0.5 or 1.5% EHA, but not in other groups. Cholesterol levels were higher in all male rat test groups and in female rats and male and female mice fed either 0.5 or 1.5% EHA, although this effect was reversible following a 28-day recovery period. The principal effects of EHA involved the liver or metabolic processes associated with the liver. The 0.5 and 1.5% diets in both rats and mice were associated with increased relative liver weight and histological changes in hepatocytes, specifically hepatocyte hypertrophy and reduced cytoplasmic vacuolization. Observed histopathological and clinical pathological changes were reversible following recovery. These results indicate that EHA does not produce persistent. overt toxicity in rats or mice following subchronic dietary exposure at concentrations up to 1.5% in feed. The no-observed-adverse-effect level (NOAEL) for male rats was 61 mg/kg/day and the no-observed-effect level (NOEL) for female rats was 71 mg/kg/day, while 180 and 205 mg/kg/day represent NOELs for male and female mice, respectively.

Subchronic inhalation toxicity study of a water-dispersible polyester in rats.

AQ55 is a high molecular weight, water-dispersible, amorphous polyester used in applications where the exclusion of solvents and conventional surfactants is desirable, such as water-based adhesives, coatings, emulsions, paint primers, cosmetics and detergents. Potential health effects were evaluated in rats exposed by inhalation for about 13 wk to mean concentrations of 0, 2.4, 19.6 or 199 mg/m3 AQ55 polymer. No mortality occurred and body weights were unaffected. Mean relative liver weights in all treated male groups were slightly higher than control weights, but were not judged to be treatment related. Absolute liver weights and all other organ weights except lung weights were normal. Haematology, clinical chemistries and gross pathology were unremarkable. Exposure-related changes in the 199 mg/m3 groups included increased mean absolute and relative lung weights, accumulations of macrophages and acute inflammatory cells in alveolar and bronchial lumina, and increased numbers of macrophages in sinusoids of peribronchial lymph nodes. Minor accumulation of macrophages in alveolar lumina was the only exposure-related change in the 19.6 mg/m3 group. No exposure-related effects were seen in the 2.4 mg/m3 group. AQ55 produced no systemic toxicity, and aerosols of AQ55 do not appear to be toxic to pulmonary tissues following subchronic inhalation exposure.

Role of cell-mediated immunity (CMI) in chickens inoculated with avian leukosis/sarcoma virus.

Immunosuppression of chickens infected in ovo with avian leukosis virus (RAV-1) by the injection of antilymphocyte serum (ALS) did not significantly (P > 0.05) alter the incidence or distribution of lesions in chickens between 3 and 6 months of age as compared to control groups. Antilymphocyte serum treatment of Rous sarcoma virus [RSV (RAV-2)]-infected chickens significantly (P < 0.05) inhibited tumour regression and enhanced tumour metastasis. It was concluded that cell-mediated immunity was not a significant factor in effecting the survival of viraemic chickens Viraemic leukosis virus infected-chickens responded as well as normal chickens to sensitization to Mycobacterium tuberculosis H37Ra. The results were based on in vivo wattle tests and in vitro cell-mediated cytotoxicity assays. It was concluded that subclinical avian leukosis virus infection had no effect on the thymus-dependent lymphocyte (T-cell) population associated with cutaneous delayed hypersensitivity and cell-mediated cytotoxicity.

The attempted immunization of turkey hens with viable Mycoplasma meleagridis.

The attempted immunization of 53 female Broad Breasted White turkeys with five weekly 1.0 ml injections of viable Mycoplasma meleagridis, when combined with insemination with M. meleagridis infected semen, did not produce immunity but only imposed additional infection. This was detrimental to the offspring by increasing the incidence and severity of air sac lesions.